RAI: Disable huge pages for all mmap'ed memory

Prevent transparent huge pages (THP) overallocating pysical memory.

Co-authored-by: Adnan Alhomssi <[email protected]>

Author: kpamnany

src/gc-pages.c

@@ -47,6 +47,10 @@ char *jl_gc_try_alloc_pages_(int pg_cnt) JL_NOTSAFEPOINT
                             MAP_NORESERVE | MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
     if (mem == MAP_FAILED)
         return NULL;
+
+#ifdef MADV_NOHUGEPAGE
+    madvise(mem, pages_sz, MADV_NOHUGEPAGE);
+#endif
 #endif
     if (GC_PAGE_SZ > jl_page_size)
         // round data pointer up to the nearest gc_page_data-aligned

src/gc-stacks.c

@@ -61,6 +61,9 @@ static void *malloc_stack(size_t bufsz) JL_NOTSAFEPOINT
         munmap(stk, bufsz);
         return MAP_FAILED;
     }
+#ifdef MADV_NOHUGEPAGE
+    madvise(stk, bufsz, MADV_NOHUGEPAGE);
+#endif
 #endif
     jl_atomic_fetch_add(&num_stack_mappings, 1);
     return stk;

src/gc.c

@@ -4000,6 +4000,9 @@ void *jl_gc_perm_alloc_nolock(size_t sz, int zero, unsigned align, unsigned offs
     errno = last_errno;
     if (__unlikely(pool == MAP_FAILED))
         return NULL;
+#ifdef MADV_NOHUGEPAGE
+    madvise(pool, GC_PERM_POOL_SIZE, MADV_NOHUGEPAGE);
+#endif
 #endif
     gc_perm_pool = (uintptr_t)pool;
     gc_perm_end = gc_perm_pool + GC_PERM_POOL_SIZE;